title: Cancer risk in patients with Hashimoto's thyroiditis: a nationwide cohort study.
abstract: BACKGROUND
  This study examined the risk of cancer in patients with Hashimoto's thyroiditis (HT).
  
  
  METHODS
  The Taiwanese National Health Insurance Research Database (NHIRD) was used to identify 1521 newly diagnosed HT patients from 1998-2010, and 6084 frequency-matched non-HT patients. The risk of developing cancer for HT patients was measured using the Cox proportional hazard model.
  
  
  RESULTS
  The incidence of developing cancer in the HT cohort was 5.07 per 1000 person-years, which was 1.68-fold higher than that in the comparison cohort (P<0.001). Compared with patients aged 20-34 years, patients in older age groups had a higher risk of developing cancer (35-55 years: hazard ratio (HR)=5.96; >55 years: HR=9.66). After adjusting for sex, age, and comorbidities, the HT cohort had HRs of 4.76 and 11.8 for developing colorectal cancer and thyroid cancer, respectively, compared with non-HT cohort. Furthermore, the HT cohort to non-HT cohort incidence rate ratio (IRR) of thyroid cancer was higher in the first 3 years (48.4, 95% confidence interval (CI)=35.0-66.3), with an adjusted HR of 49.4 (95% CI=6.39-382.4).
  
  
  CONCLUSIONS
  Hashimoto's thyroiditis patients have a higher risk of thyroid cancer and colorectal cancer. The thyroid cancer prevention effort should start soon after HT is diagnosed, while being cautious of colorectal cancer increases with time.
authors.affiliation: 1] Department of Nuclear Medicine and PET Center, Taipei, Taiwan [2] School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Y-K
authors.initials: YK
authors.lastname: Chen
authors.forename: C-L
authors.initials: CL
authors.lastname: Lin
authors.forename: F T-F
authors.initials: FT
authors.lastname: Cheng
authors.forename: F-C
authors.initials: FC
authors.lastname: Sung
authors.forename: C-H
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D050031:Hashimoto Disease / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology*; D012306:Risk; D013624:Taiwan / Q000453:epidemiology